In recent years, a sputter neutral particle mass spectrometry apparatus using a focused ion beam device and a laser oscillation device has been developed. In this apparatus, an ion beam generated in a column inside an ion beam device is irradiated on a particular region of a sample to perform sputtering. A laser is irradiated on neutral particles which have been sputtered in the above manner, and neutral particles generated according to ion beam scanning are mass separated/detected by a mass spectrometer to obtain a scanned image (For example, see Patent documents 1 and 2).
In laser SNMS measurements provided with a focused ion beam device, a beam diameter of a primary ion beam is as small as a few tens of nanometers (nm), and therefore is susceptible to contamination by water, oxygen, carbon hydride, etc. distributed on the surface of a measurement sample when compared to a secondary ion mass spectrometry apparatus. Therefore, even within a same sample, the quantification results of a detected element would differ depending on where the primary ion beam is irradiated. Therefore, it would be difficult to maintain reproducibility with high accuracy.
Since the primary ion beam diameter is small in the above-mentioned laser SNMS measurements, the ionization rate of the neutral particles in post-ionization is easily influenced by where the laser is irradiated. Since the ionization cross-section would differ depending on the element, it is necessary to accurately ascertain and control the position of the laser condensing spot when carrying out measurement. However, since the position of the laser condensing spot is controlled by the signal amount of the ion detected by the mass spectrometer, it has been impossible to separate factors such as primary ion beam irradiation, laser irradiation, and drawing-in timing conditions of a secondary ion, and to unify laser irradiation conditions between the measurement samples. Therefore, it has been difficult to maintain the quantitativeness of measurements.
In recent years, in measurements using a time of fly secondary ion mass spectrometer (TOF-SIMS) in which focused ion beams (FIB) are the primary ion beams, and a laser SNMS device, a sputter neutral particle mass spectrometry apparatus which maintains quantitativeness of measurements by unifying laser irradiation conditions between measurement samples, resulting in high sensitivity and high reproductivity, has been required.